programmemory.cpp: avoid unnecessary infer() calls in `Executor::ex…

…ecuteimpl()` (#6629)

`infer()` will exit early if any of the list of given values is empty.
so there is no need to call it (and copy the values with the call) if we
know that beforehand.

lib/programmemory.cpp

@@ -1506,13 +1506,13 @@ namespace {
                 if (!lhs.isUninitValue() && !rhs.isUninitValue())
                     r = evaluate(expr->str(), lhs, rhs);
                 if (expr->isComparisonOp() && (r.isUninitValue() || r.isImpossible())) {
-                    if (rhs.isIntValue()) {
+                    if (rhs.isIntValue() && !expr->astOperand1()->values().empty()) {
                         std::vector<ValueFlow::Value> result =
                             infer(ValueFlow::makeIntegralInferModel(), expr->str(), expr->astOperand1()->values(), {std::move(rhs)});
                         if (!result.empty() && result.front().isKnown())
                             return result.front();
                     }
-                    if (lhs.isIntValue()) {
+                    if (lhs.isIntValue() && !expr->astOperand2()->values().empty()) {
                         std::vector<ValueFlow::Value> result =
                             infer(ValueFlow::makeIntegralInferModel(), expr->str(), {std::move(lhs)}, expr->astOperand2()->values());
                         if (!result.empty() && result.front().isKnown())